brightness 
 
-  Type: Integer
  -  Range / Valid values: 0 - 255
  -  Default: 0 (disabled)
  -  Group: Video Devices
 
 
The brightness level for the video device., The brightness level for the video device.
Value 0 means that Motion does not set the brightness value but leaves it unchanged.
If this setting is used in conjunction with the 
auto_brightness feature, then this setting is the average brightness level in the range 1 (dark) to 255 (bright) that the auto_brightness feature will try to achieve by adjusting the device brightness up and down.